July 23, 2023, 11:36 am | Read time: 3 minutes
Foxglove, forget-me-not, and pansy can be purchased. Or you can sow them in the garden–a year before they bloom. Because summer flowers need time.
Some flowers have a unique life rhythm. In the first year, only their leaves develop, and in the following spring or summer, they bloom. If you want these so-called biennial summer flowers in your garden bed, you need to sow them in mid-summer.
Which Summer Flowers Are Biennial?
- Wallflower (Erysimum cheiri)
- Forget-me-not (Myosotis)
- Horned violet (Viola cornuta)
- Pansy (Viola x wittrockiana)
- Iceland poppy (Papaver nudicaule)
- Sweet William (Dianthus barbatus)
- Foxglove (Digitalis purpurea)
Sowing Time
Hanna Strotmeier, a master gardener at a trial garden in Füchtorf in the Münsterland region, recommends sowing from mid-July. However, you shouldn’t wait too long. The biennial species need to produce enough leaf mass in the fall to push out many flower stems in the second year. Therefore, biennials should be sown by mid-August to September at the latest.
“Sowing too early doesn’t offer any advantages either, as the plants become too densely leafed before winter and poorly ventilated,” says Marion Jentzsch, a horticultural engineer and ornamental plant cultivation consultant at the Saxon State Office for Environment, Agriculture, and Geology.
Tips for Sowing
The seeds are best placed in trays, advises master gardener Hanna Strotmeier. Once the seeds have germinated, the seedlings should be spaced apart so each has more room to grow. Once the plants reach a certain size, they can be transplanted into the garden soil at their final location. “This way, each plant develops a strong root ball,” says Hanna Strotmeier.
“Overall, sowing is uncomplicated,” says Marion Jentzsch. But you need to water well, as seeds won’t germinate in dry conditions. Her tip: Use a sieve to sprinkle some substrate on light germinators like Sweet William and foxglove, whose seeds usually sit on the soil rather than in it. This helps retain moisture around the seed. Alternatively, cover the sowing with fleece or perforated foil.
Related: When is the right time to plant summer flower bulbs?
Heat Protection
Although biennials are accustomed to summer temperatures, it shouldn’t get too warm for sowing. If temperatures exceed 77 degrees Fahrenheit, Hanna Strotmeier advises placing the trays in a cool basement after sowing–especially containers with pansies.
Only when the first leaves appear should the trays be moved to a bright and warmer place. However, direct summer sun should be avoided.
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Combination in the Bed
“Since biennial flowers bloom fully in spring, bulb flowers are a good complement,” says Marion Jentzsch. Hanna Strotmeier also recommends this. Specifically: Combine forget-me-nots and pansies with early-blooming tulip varieties. Grape hyacinths and daffodils pair well with wallflowers.
For flower pots and balcony boxes, the master gardener suggests short-stemmed wild tulips and low Tête-à-Tête daffodils as partners. Two biennials are particularly suitable here because they bloom for a long time: the horned violet and the forget-me-not.
Risk of Confusion with Biennial Summer Flowers
Breeders have developed annual varieties from some biennials that bloom in the year of sowing. This is the case with Canterbury bells, Sweet William, Iceland poppy, or foxglove. Marion Jentzsch advises: “Hobby gardeners are well advised to read the cultivation instructions on the seed packets carefully.”
with material from dpa